1. Field of the Invention
The present invention generally relates to a balanced transmission connector. For example, a balanced transmission connector is configured to input/output signals by using balanced transmission with a pair of contacts arranged in parallel.
2. Description of the Related Art
As for methods of transmitting data, there is a typical data transmitting method using a single electric wire. Another method is a balanced transmission method using a pair of electric wires. With the balanced transmission method, positive (+) signals are transmitted simultaneously with negative (−) signals having the same size but different polarities as the positive signals. The balanced transmission method has an advantage of being less susceptible to noise compared to the typical data transmitting method and is widely used in fields of transmitting signals at high speed.
A balanced transmission connector includes plural pairs of contacts arranged in parallel and has each contact with a lead part connected to a substrate wherein each pair of contacts has an input signal contact and an output signal contact positioned one on top of the other (See, for example, Japanese Laid-Open Patent Publication No. 2004-355819).
Next, a configuration of a balanced transmission connector 50 of a related art example is described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of the balanced transmission connector 50 of the related art example. FIG. 2 is an exploded perspective view of the balanced transmission connector 50 of the related art example.
As illustrated in FIGS. 1 and 2, the balanced transmission connector 50 has an insulation block 60, pairs of contacts (contact pair) 80, and planar ground contacts 90 assembled thereto. The insulation block 60 is a molded component made of a synthetic resin material having an electrical insulating property. Each pair of contacts (contact pair) 80 is formed of first and second signal contacts 81-1, 81-2. The pair of first and second signal contacts 81-1, 81-2 and the ground contacts 90 are alternately arranged at predetermined intervals. Further, throughout the entire length of the first and second signal contacts 81-1, 81-2 (length of first and second signal contacts 81-1, 81-2 in Y2-Y1 direction), the pairs of first and second signal contacts 81-1, 81-2 are positioned between adjacent ground contacts 90.
The insulation block 60 includes a main body portion 61, supporting portions 62, 63 extending from the X1 and X2 sides of the main body portion 61 to the Y1 direction, a planar connector portion 64 projecting from the main body portion 61 to the Y2 direction (front direction), a position restricting portion 65 arranged between the supporting portions 62, 63 and projecting from the main body portion 61 to the Y1 direction (rear direction), and boss portions 66 arranged on corresponding bottom surfaces of the supporting portions 62, 63.
A bottom portion of the main body portion 61 is mounted on an upper surface of a substrate 30. The connector portion 64 is connected to a connection slot 21 of a balanced transmission connector 20.
Slits 70 and pairs of first and second tunnels 71, 72 are alternately formed at predetermined intervals in the main body portion 61. The slits 70 are formed in the main body portion 61 corresponding to the ground contacts 90, and the pairs of first and second tunnels 71, 72 are formed in the main body portion 61 corresponding to the pairs of first and second signal contacts 81-1, 81-2. Further, slits 73, upper grooves 74, and lower grooves (not illustrated) are formed in the connector portion 64. The slits 73 are formed in a manner continuing from the slits 70. The upper grooves 74 are formed continuing from the first tunnels 71. The lower grooves are formed continuing from the second tunnels 72. Further, slits 76, 77, and 78 are formed at a Y1 side edge of the position restricting portion 65.
The ground contact 90 includes a planar base portion 91, a ground contact portion 92 extending from the base portion 91 in the Y2 direction, and an L-shaped lead portion 93 extending from a Y1-Z2 edge of the base portion 91 in the Y1 direction.
The first signal contact 81-1 includes a base portion 82-1, a rod-like signal contact portion 83-1 projecting from the base portion 82-1 in the Y2 direction (front direction), a length adjustment portion 84-1 extending from the base portion 82-1 in a downward diagonal direction (direction between directions Y1 and Z2), a substantially L-shaped orthogonal lead portion 85-1 extending from a Y1 edge of the length adjustment portion 84-1, and a horizontal direction lead portion 86-1 extending from a Z2 edge of the orthogonal lead portion 85-1 in the Y1 direction (rear direction).
The second signal contact 81-2 includes a base portion 82-2, a signal contact portion 83-2, a length adjustment portion 84-2, an orthogonal lead portion 85-2, and a horizontal lead portion 86-2. The second signal contact 81-2 basically has the same shape as the first signal contact 81-1 except that the length adjustment portion 84-2 extends from a X1 edge part of the base portion 82-2 in an upward diagonal direction.
The ground contacts 90 and the first and second signal contacts 81-1, 81-2 are assembled to the insulation block 60 by being pressingly inserted from the Y1 direction (rear direction).
By pressingly inserting the ground contact 90 in the slit 70 from the ground contact portion 92, the base portion 91 is inserted through the slit 70 and positioned in the slit 73. A Z1 edge surface 92b and a Z2 edge surface of the ground contact portion 92 are exposed on the Z1, Z2 surfaces of the connector portion 64. Further, substantially half of a Y1 portion of the base portion 91 projects from the main body portion 61 in the Y1 direction (rear direction). Further, Z2 projecting portions 91b1 of the base portion 91 and the lead portions 93 are engaged in the slits 76. Accordingly, the positions of the lead portions 93 are restricted in the X1-X2 directions.
By pressingly inserting the first signal contact 81-1 in the tunnel 71 from the signal contact portion 83-1, the signal contact portion 83-1 is inserted through the tunnel 71 and positioned in the upper groove 74. The base portion 82-1 is positioned inside the tunnel 71. The signal contact portion 83-1 is exposed on a Z1 surface of the connector portion 64. The length adjustment portion 84-1, the orthogonal lead portion 85-1, and the horizontal lead portion 86-1 project in the Y1 direction (rear direction). Further, a portion of the lead portion 85-1 positioned closer toward the horizontal lead portion 86-1 engages the slit 77. Accordingly, the positions of the lead portions 86-1 are restricted in the X1-X2 directions.
The ground contact portions 92 and the pairs of signal contact portions 83-1, 83-2 are arranged at intervals p1. The lead portions 93, 86-1, and the 86-2 are aligned on a bottom surface (X-Y surface) of the insulation block 60.
The first and second signal contact portions 83-1, 83-2 are arranged in parallel in a vertical direction (Z1-Z2 direction) at the front and the inside of the balanced transmission connector 50 whereas the first and second signal contact portions 83-1, 83-2 are arranged in a manner slightly diverted in the horizontal direction (X1-X2) at the rear of the balanced transmission connector 50. Accordingly, the orthogonal lead portions 85-1, 85-2 of the first and second signal contact portions 83-1, 83-2 and the horizontal lead portions 86-1, 86-2 have different lengths. This results in a problem of changing the impedance characteristics.
With the balanced transmission connector 50, the entire length of the orthogonal lead portions 85-1, 85-2 and the horizontal lead portions 86-1, 86-2 becomes long because the horizontal lead portions 86-1, 86-2 are formed in a manner projecting rearward of the ground contacts 90. Thereby, more elements become subject to the change of impedance characteristics as the entire length of the orthogonal lead portions 85-1, 85-2 and the horizontal lead portions 86-1, 86-2 increases. As a result, a larger ground contact 90 would be required for preventing cross-talk between the orthogonal lead portions 85-1, 85-2 and the horizontal lead portions 86-1, 86-2.